1. Abstract Our client desires a device to detect the electrical activity of the bladder during the voiding process. The device will be used in a urodynamics lab in conjunction with diagnostic tools. The final design incorporates external and internal electrodes, an EMG circuit, and a digital oscilloscope.

2. Motivation Overactive Bladder (OAB): A sudden urge to urinate immediately followed by a bladder contraction, resulting in involuntary micturition Affects 33 million Americans May cause urinary incontinence Limited treatment options Disposable pads Medication Catheters

3. Problem Statement Bladder EMG has never been consistently detected Frequency and magnitude of electrical signal are not well established Pelvic bone and abdominal muscles distort/interfere with signal detection

4. Bladder Composition Epithelium Lamina propria Detrusor muscle Provides force required to void Three layers of smooth muscle Perivesical soft tissue

5. LALA

6. Micturition Urine exits the bladder through the urethra Outflow is controlled by muscles called sphincters, which surround the urethra The sphincters and pelvic floor muscles under the bladder keep the urethra closed Micturition is initiated by the contraction of the detrusor and relaxation of the sphincter/pelvic floor muscles

7. Client Requirements Noninvasive method Store and print signal/data Applicable to males and females Compatible with urodynamic tests Accurate Juxtapose pressure and electrical signals

8. Previous Research Netherlands study Six surface electrodes Extensive digital signal processing Inconclusive results Sample Recording

9. Design Alternatives Electrode Design Memory Alloy Constellation Suction Needle Electrode Placement Vaginal Rectal Urethral

10. Final Design Internal and External Electrodes Obtain signal Reduce noise EMG Circuit Amplify and filter signal Reject DC offset Digital Oscilloscope Display signal

11. Motion Artifact Fact: Netherland study recorded a 0.5 mV change during micturition Problem: Surface electrodes can cause skin motion artifact greater than 0.5 mV Question: Is the 0.5 mV signal from the bladder or a result of skin motion artifact? Solution: Abrade the skin to eliminate skin motion artifact

12. EMG Circuit Gain: 1775 High pass frequency: 60.2 Hz Low pass frequency: 0.005 Hz CMRR: 105.54 dB

13. EMG Circuit Diagram

14. Electrodes External Electrode Ag-Ag/Cl surface electrodes Located above and below pubic bone Internal Electrode 1 mm diameter, 2.5 mm pellet 10 mm silver wire Sintered and re-useable Inserted in 5 French catheter Sealed with epoxy

15. Digital Output Device Digital Oscilloscope Storage Real-time viewing capacity

16. Preliminary Testing: Catheter Electrode Signal measured from a sinusoidal input

17. Preliminary Testing: Surface Electrodes Signal measured during micturition

18. Future Work Create protocol Fine tune the circuit Obtain a clear signal Develop computer software Test extensively Clinical Setting Statistical Analysis data

19. References Ballaro A, Mundy AR, Fry CH, and Craggs MD. Bladder electrical activity: the elusive electromyogram. BJU International, 2003. 92: 78-84. “Catheters and Transducers.” Medtronic. http://www.medtronic.com/neuro/mfd/consumables/acc_cat_2k1_trans.pdf September 25, 2003. Kinder MV, van Waalwijk ESC, Gommer ED, and Janknegt RA. A non-invasive method for bladder electromyography in humans. Archives of Physiology and Biochemistry, 1998. 106: 2-11. “Pelvic Soft Tissue Structures.” Barts and the London, Queen Mary’s school of Dentistry and Medicine. http://www.mds.qmw.ac.uk/biomed/kb/grossanatomy/basic_anat/pelvic_soft.ht m September 25, 2003. Kinder MV, van Waalwijk ESC, Gommer ED, and Janknegt RA. A non-invasive method for bladder electromyography in humans. Archives of Physiology and Biochemistry, 1998. 106: 2-11. “TECA NCS Disposable Surface Electrodes.” Oxford Instruments. http://www.oxford-instruments.com/MDCPDP346.htm September 25, 2003. Paul Victorey, Biomedical Engineering Department, UW-Madison